The present invention relates to a linear slide bearing suitable for use in various sliding parts such as the table saddle of a machine tool, the slider of a machining center, and the slider of a transportation robot for reciprocative transportation of a heavy object. More particularly, the present invention pertains to a linear slide bearing having an automatic aligning function
In a typical conventional linear slide bearing, as shown in FIG. 21, for example, a main body 110 of the bearing has longitudinal recesses 111, 112 respectively fitted with bearing races 113, 114 of rectangular cross-section similarly extending in the longitudinal direction of the main body 110. The bearing races 113, 114 are screwed to the recesses 111, 112 to form respective loaded ball passages between loaded ball grooves 116, 117 on the bearing races 113, 114 and loaded ball grooves 119, 120 on a track shaft 118. Further, the loaded ball grooves 116, 117, 119, 120 and their corresponding non-loaded ball grooves are communicated with each other to form respective endless tracks through which balls are recirculated, thereby allowing the main body 110 to effect a linear slide motion.
When a transportation robot, for example, is to be constructed by employing a linear slide bearing having the above-described construction, a plurality of track shafts 118 are generally laid such as to extend coaxially in the longitudinal direction under the necessity of enlarging the transportation operation range. In the case where the track shafts 118 are laid over a long distance, however, mounting errors or other failures may prevent the longitudinal axes of the track shafts 118 connected to each other from aligning with each other on a straight line, so that the lined track shafts 118 may horizontally or vertically bend disadvantageously. In such case, since the upper surfaces 113a, 114a and rear surfaces 113b, 114b of the bearing races 113, 114 are respectively closely secured to the wall surfaces of the recesses 111, 112 of the main body 110 according to the conventional construction, the contact pressure of the balls locally increases when the main body 110 passes the bent portion of the lined track shafts 118, thus causing dents in the surfaces of the loaded ball grooves 116, 117, 119, 120. Also, when passing the bent portion of the lined track shafts 118, the main body 110 encounters an increased resistance to its sliding motion, so that it is not possible to ensure a smooth linear slide motion of the main body 110.